Fuel pump issue I guess??

[maxum_man]

On a 1987 Mercruiser 4.3L 205 SN: 0B768xxx with mechanical fuel pump. I just installed a new (reman) long block and finally figured out some electrical issues {with a little help }. Anyhow, I filled the float bowl with a syringe and it ran for about 15-20 seconds and died. I pulled the fuel line off the anti siphon valve on the tank and stuck it in a bucket with gas in it to see if it was that valve not working properly. It still died after about 15 seconds and filling the bowl again. So...I'm guessing I need a fuel pump? No gas is in the sight tube, but I'm guessing that doesn't necessarily mean anything if I'm still not getting any fuel from the tank to the carb. What do you guys think?

 

[Scott Danforth]

did you pre-fill the fuel/water separator filter? or did you just screw on a dry one? if so, fill the carb about 2 or 3 more times, or fill the filter

 

[alldodge]

Being a 1987 you should have the fuel filter as part of the pump.
http://www.mercruiserparts.com/bam/subassembly/31474/951/90

I would think your pump is bad, but to make sure, remove the fuel line from the carb and place it so it pumps into a container. Crank the motor and see if fuel comes out. If it does come out then connect a vacuum fuel pressure gauge between the carb and pump and measure pressure, should be 3 to 7 psi.

 

[salty3rd]

A Stuck float in the Carb could also cause this issue

 

[bentle]

Plugged fuel vent line to the tank, plugged fuel line pre filter in the tank, loose or broken fuel pickup tube in tank, and bad fuel pump not pumping fuel. Verify if your getting fuel to your carb and if yes then could be a sticky closed float in your carb.
If no fuel to the carb then it's somewhere between your pump and tank.